Eye and gaze tracking systems have been implemented in various applications to track a user's eye movements and/or the direction in which the user is looking (i.e., the user's gaze direction). The range of such applications extends from serious (e.g., airport security systems) to playful (e.g., video game avatar renderings). Typical eye tracking systems may use various technologies to track a user's eye movements and/or gaze direction. Many of those technologies rely on light reflected by the person's eye and various relationships between the parts of the eye (e.g., the structure of the eye and the contrast between parts of the eye). For example, eye and gaze tracking systems may employ limbus tracking, pupil tracking, Purkinje tracking, and/or other tracking mechanisms (e.g., based on reflected light or other characteristics).
In many implementations, an infrared (IR) camera includes high-intensity IR light sources that are used to illuminate a person's eye in conjunction with IR sensors that are used to detect the reflections (i.e., glints or Purkinje images) from the person's retina/cornea. The precision and accuracy of the gaze estimations are largely a function of the ability to accurately detect and identify various characteristics of the reflections (e.g., location and intensity). Additionally, the high-intensity light used for illumination may result in a significant amount of power consumption, particularly for imaging devices and other mobile computing devices.